Densification of chlorine-doped continuous CNT sheet/polyvinylidene fluoride sandwich film and improvement of the mechanical and dielectric properties

The compact structure of a chlorine-doped continuous CNT sheet/polyvinylidene fluoride (Cl-CNT sheet/PVDF) was successfully optimized by means of a hot-press treatment to improve the mechanical and dielectric properties with a high densification degree. Then, the densified Cl-CNT sheet/PVDF dielectric layer was inserted between two PVDF insulating layers to fabricate a sandwich composite. It was found that the dielectric and mechanical properties were effectively enhanced, with a dielectric permittivity of 40.4 (@10² Hz), a dielectric loss of 0.16 (@10² Hz), a tensile strength of 139 MPa, and a tensile modulus of 4.4 GPa under a hot-pressing pressure of 20 MPa. Furthermore, the densified Cl-CNT sheet/PVDF was used as an electrode in a multilayer sandwich composite film, and good performance was obtained. The improvement mechanism was discussed and the studied CNT composite and other dielectric composites were compared. It demonstrates great potential for applications in dielectric and electrode materials to achieve structural and functional integration.